title: SarZ promotes the expression of virulence factors and represses biofilm formation by modulating SarA and agr in Staphylococcus aureus.
abstract: Staphylococcus aureus is a remarkably adaptable organism capable of multiple modes of growth in the human host, as a part of the normal flora, as a pathogen, or as a biofilm. Many of the regulatory pathways governing these modes of growth are centered on the activities of two regulatory molecules, the DNA binding protein SarA and the regulatory RNAIII effector molecule of the agr system. Here, we describe the modulation of these regulators and their downstream target genes by SarZ, a member of the SarA/MarR family of transcriptional regulators. Transcriptional and phenotypic analyses of a sarZ mutant demonstrated that the decreased transcription of mgrA and the agr RNAIII molecule was accompanied by increased transcription of spa (protein A) and downregulation of hla (alpha-hemolysin) and sspA (V8 protease) transcripts when compared to its isogenic parent. The decrease in protease activity was also associated with an increase in SarA expression. Consistent with an increase in SarA levels, the sarZ mutant displayed an enhanced ability to form biofilms. Together, our results indicate that SarZ may be an important regulator governing the dissemination phase of S. aureus infections, as it promotes toxin expression while repressing factors required for biofilm formation.
authors.affiliation: Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, NH 03755, USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Tamber
authors.forename: Ambrose L
authors.initials: AL
authors.lastname: Cheung
mesh_terms: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins / Q000096:biosynthesis*; D018441:Biofilms / Q000254:growth & development*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D010447:Peptide Hydrolases / Q000096:biosynthesis; D013211:Staphylococcus aureus / Q000502:physiology*; D015534:Trans-Activators / Q000096:biosynthesis*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors / Q000096:biosynthesis*
chemical_list: C095698:Agr protein, Staphylococcus aureus; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C492107:SarA protein, Staphylococcus aureus; C534537:SarZ protein, Staphylococcus aureus; D015534:Trans-Activators; D014157:Transcription Factors; D037521:Virulence Factors; D010447:Peptide Hydrolases